Endoscope and method for assembling components of an optical system

ABSTRACT

An endoscope has a tubular shaft whose interior contains components, in particular lenses, spacers, diaphragms, prisms and filters of an optical system, said components being at least partially surrounded by a support piece made of shrunk material. It is proposed that the components be surrounded by a transparent and tube-sleeve-shaped shrunk material which has been shrunk before the components are introduced into the tubular shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of pending U.S. patent application Ser.No. 11/206,562 filed Aug. 18, 2005, which in turn is a continuation ofinternational application PCT/EP 2004/000765 filed on Jan. 29, 2004which designates the United States and which claims priority of Germanpatent application No. 103 07 904.1 filed on Feb. 18, 2003. All priorapplications are herein incorporated by reference.

BACKGROUND OF THE INVENTION

The invention relates to an endoscope, with a tubular shaft whoseinterior contains components, in particular lenses, spacers, diaphragms,prisms and filters of an optical system, said components being at leastpartially surrounded by a support piece made of shrunk material.

The invention also relates to a method for assembling components, inparticular lenses, spacers, diaphragms and filters of an optical systemin the interior of a tubular shaft of an endoscope, said componentsbeing surrounded by a support piece made of shrunk material.

Such an endoscope and such a method are known from document DE 197 32991 C2.

In the method disclosed in the latter document, the shrinkable materialis used to fix the components of the optical system in the tubularshaft. To do this, the components are introduced into a support piecemade of shrinkable material at least partially surrounding saidcomponents, and this unit is then pushed into the tubular shaft. Thedimensions are such that a small gap remains between the outside face ofthe support piece and the inside face of the tubular shaft. As thematerial shrinks, it expands slightly in the radial direction and fillsthe gap, so that in this way the unit is fixed on the inside face of thetubular shaft.

DE 39 12 720 C2 also discloses the use of a plastic shrinkable tube forpositioning the elements of a relay lens system of an endoscope. Thematerial is chosen such that it does not transmit light, i.e. is opaque.This is intended to ensure that light does not pass from the light guideinto the area of the relay lens system or into the area of the objectivelens and there cause reflections or glare. The lenses of the lens systemcan first be placed in a correct position. The shrinkable tube is thenshrunk by application of heat so that it holds the lenses, without alens fixture in the conventional sense being needed.

This construction is intended to make it possible to produce endoscopesextremely inexpensively, and provision is therefore also made to producethe lenses from plastic.

In the document DE 39 12 720 C2 mentioned earlier, the aim is to fix theexpensive components of the optical system to the inside face of a metaltubular shaft by using the shrink properties of the material surroundingthese components.

It is an object of the present invention is to further optimize anendoscope and a method for assembling components in such a way that, byusing shrinkable materials, it is possible to fix the optical componentsrelative to one another in a way which can also be checked.

SUMMARY OF THE INVENTION

According to the invention, the object in respect of an endoscope isachieved by the fact that the components are surrounded by a transparentand tube-shaped shrunk material which has been shrunk before thecomponents are introduced into the tubular shaft.

According to the invention, the object in respect of a method isachieved by the following steps, namely introducing the components intoa transparent and tube-shaped shrinkable material to form a unit,shrinking the material to fix the position of the components relative toone another, checking the position of the components relative to oneanother through the transparent shrunk material, and introducing theunit composed of shrunk tube-shaped material, and the componentscontained therein, into the tubular shaft.

The optical system of an endoscope is made up of a succession ofdifferent optical components. A particularly good image quality can beobtained using what are referred to as rod lenses. For this purpose,several rod lenses separated from one another by spacers are arranged inseries, and other components such as diaphragms, filters or coverglasses or prisms can additionally be provided.

For a good image quality, it is not only necessary for these parts to beprecisely oriented relative to one another and fixed axially along anoptical axis; it is also necessary for their relative rotation positionsto be unchangeable. In the course of assembly, it is expedient to checkthe optical image qualities of such a lens system so that, ifappropriate, systems with optical misalignments can be eliminated.

The quality check of the optical system is normally made only aftercomplete assembly of the endoscope. If optical errors are found, it isthen very expensive to correct these, and in most cases the endoscopehas to be completely dismantled.

With the present invention, it is now possible to produce a unitcomposed of the optical components and the tube outside the endoscopeand to check this unit visually. For this purpose, a transparentshrinkable material is used which in many respects affords advantagesover the opaque materials known from the prior art. On the one hand, theposition of the components relative to one another can be visuallychecked at the time the individual components are introduced into thematerial before it has been shrunk. In particular, it is possible toestablish whether, for example, individual filter components ordiaphragms have turned relative to one another, or whether, for example,a gap is or is not present between a spacer and a rod lens.

It is also possible to check the correct arrangement of the lenscomponents, lenses, spacers and, if appropriate, diaphragms, filtersand/or prisms.

After this unit has been shrunk, a check can once again be made, namelyas to whether the shrinking has caused any relative changes to takeplace. During shrinkage, the material surrounding the optical elementsmoves. By provision of the transparent material, it is now possible forthe first time to perform a visual check even after the shrinkingprocess. Of course, checks are also already possible in the direction ofthe optical axis that is to say through the optical elements. Thus, sucha preliminary check can be made even before the optical system is fittedin the shaft. After introduction of the shrunk unit and finalpositioning of this unit in the shaft, a final check can then also bemade.

In this way, the reliability of the assembly and the assembly as such,can also be simplified and improved.

In a further embodiment of the invention, all the components aresurrounded by a single tube of transparent and shrunk material.

This measure has the advantage that all the components are introducedinto a single tube-shaped body and this unit can be handled as suchafter shrinking, for example can be simply inserted as a unit into thetubular shaft of the endoscope. This unit can be introduced into theendoscope shaft in the appropriate position of rotation or can bebrought to the correct position of rotation after introduction. If, forexample, a front closure forms a prism with a lateral angle of view, theposition, that is to say lateral angle of view, can be chosen to theleft, to the right, upward or downward.

In a further embodiment of the invention, the components are fixed tothe inside face of the tubular shaft via the tube-shaped shrunkmaterial.

There are a great many ways of doing this, for example by adhesivefixation where the adhesive can be applied before introduction of theunit, or can be introduced for fixing after introduction through radialbores in the tubular shaft.

In a further embodiment of the invention, the tube is fixed to theinside face of the tubular shaft by radial expansion of the shrunkmaterial.

This measure has the advantage that the effect, known from DE 197 32 991C2, can now additionally be used to fix the already “pre-shrunk”unit tothe inside face of the tubular shaft by a further shrinking process.This entails a further axial shrinkage with slight radial expansion.

The extent of the shrinking process can be controlled by the nature andduration of the shrink treatment. In a first preliminary shrinkingprocess, the shrink phenomenon is utilized so that the componentsintroduced into the tube can be fixed relative to one another. Afterinsertion of this unit into the tubular shaft, a further shrinkingprocess is carried out, its sole purpose being to fill the gap betweenthe outside face of the unit, composed of pre-shrunk shrinkable tube andthe components contained therein, and the inside face of the tubularshaft into which this unit is inserted, in order thereby to fix thisunit on this inside face of the tubular shaft as it experiences a slightexpansion in the radial direction during this further shrinking. Forthis purpose, certain preliminary treatments of the shrinkable tube canbe envisaged, for example one or more beads in the form of rings orpartial rings lying within the cross section. These geometric departuresfrom the otherwise cylindrical shape of the shrinkable tube entailradial expansion of the geometry of the shrinkable tube upon its axialshrinkage, without expansion of the material as such.

In one embodiment of the method, the unit composed of components and oftransparent shrinkable material is inserted, before shrinkage, into aretaining device in which the unit lies in an oriented position.

This measure has the advantage that the retaining device can provideadditional measures for keeping the unit correctly aligned. It is alsopossible, after insertion in the retaining device, to check the unit forcorrect fit before the shrink process is instigated.

The unit inserted in the retaining device can be additionally fixed by apartial vacuum.

In a further embodiment of the method, the unit is inserted into agroove of the retaining device.

This is particularly advantageous if long endoscope shafts are to befitted and in particular if there is a risk of the force of gravitycausing bending or bulging.

In a further embodiment, the unit inserted into the retaining device isweighed down by application of an object.

This measure has the advantage that not only is a support provided inthe direction of gravity by way of insertion, but bending in the senseof lifting up can be prevented by application of the object beforeshrinkage.

In a further embodiment, the object is applied with a partial form fitonto the unit.

This measure is of advantage if a great many small individual parts areassembled which have a tendency to change their position in the event ofmovements, for example during shrinkage.

It will be appreciated that the features mentioned above and those stillto be explained below can be used not only in the respectively citedcombination, but also in other combinations or singly, without departingfrom the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described and explained in greater detail below on thebasis of a number of selected illustrative embodiments and withreference to the attached drawings, in which:

FIG. 1 shows a longitudinal section through a unit composed of a tube oftransparent and shrinkable material and of optical components, namelyrod lenses and spacers, before shrinkage,

FIG. 2 shows a cross section of a retaining device in which the unitshown in FIG. 1 is inserted, specifically upon shrinkage,

FIG. 3 shows a longitudinal section through an endoscope duringassembly, into which endoscope the unit shown in FIG. 1, after it hasbeen shrunk in the retaining device 3 shown in FIG. 2, is inserted intothe tubular shaft, and

FIG. 4 shows, on a greatly enlarged scale, a partial longitudinalsection through a shaft of an endoscope in whose tubular shaft a unitaccording to the invention is inserted, the left-hand half showing theunit fixed on the inside face of the tubular shaft by adhesive contacts,and the right-hand side showing it being fixed by means of furthershrinkage.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, a unit, designated in its entirety by reference number 10,comprises a tube 12 made of transparent and shrinkable material 14. Aplurality of components 16 of an optical system are introduced into thetube 12, specifically, as viewed from left to right, a rod lens 18,whose external diameter corresponds approximately to the clear internaldiameter of the tube 12, a tubular and stiff spacer 20, a further rodlens 18′, a further spacer 21, and a further rod lens 18″.

This unit 10 is shown only by way of example, and other components suchas filters, diaphragms or the like can of course also be included. It isalso possible to provide closure windows at the ends or, in the case ofan angled side view, suitable prisms.

By virtue of the transparency of the material 14, it is possible tocheck the desired correct fit of these components 16 relative to oneanother from the outside, for example to check whether the opposing endfaces of the two rod lenses 18 and 18′ bear exactly on the spacer 20.

For the shrinking process, the unit 10 is inserted into a retainingdevice 30, as is shown in FIG. 2.

The retaining device 30 has an elongate body 32 whose length correspondsto least to the length of the unit 10.

Cut out on the top face of the body 32 there is a longitudinallyextending groove 34 which is configured in such a way that the unit 10can be inserted into this groove, the unit 10 protruding slightly abovethe upper edge of the retaining device.

A roughly plate-shaped object 36 is placed onto this protruding area andbears with an at least partial form fit on the top face of the unit 10,as it were pressing said unit 10 into the groove 34.

In this way, the unit 10 is inserted and fixed in the retaining device30 in such a way that a uniform shrinking of the material 14 of the tube12 is possible, but with the unit still being fixed in position.

Alternatively or in addition, the position can be fixed by use of apartial vacuum. For this purpose, at least one opening 35 is provided inthe bottom of the groove 34 and can be connected via an attachment piece39 to a partial vacuum source (not shown here).

As is known per se, in the actual shrinking process, energy is suppliedfrom an energy source 38 and causes the material 14 of the tube 12 toshrink.

One energy source is, for example, heat, if the material is designedsuch that it shrinks when heated. It is of course also possible to heatthe retaining device 30 itself or to cause heated fluid to flow onto theretaining device.

After the shrinkage, the object 36 is taken off and the now shrunk unit10′ is removed from the retaining device 30.

By virtue of the transparency of the material 14 which is still presenteven after the shrinkage, it is possible once again to check, from theoutside, the correct fit of the individual components 16 relative to oneanother.

The shrunk unit 10′ is then inserted into a tubular shaft 42 of anendoscope 40, as is shown in FIG. 3.

The endoscope 40 shown in FIG. 3 is represented highly schematicallyand, in addition to the tubular shaft 42 also referred to as inner tube,it also comprises an outer tube 44 of greater diameter which is mountedin a housing 50. The tubular shaft 42 is received in the interior of theouter tube 44.

As is normally the case, a light guide 46 is arranged in anapproximately crescent-shaped space between tubular shaft 42 and outertube 44, said light guide 46 leading to a laterally angled light guideattachment 48. In the illustrative embodiment shown, the light guide 46is composed of a bundle of light-conducting glass fibers. The stateshown in FIG. 3 is a state of partial assembly in which the eyepiece cupis still to be applied to the right-hand end, and, if appropriate,closure components or the like to the left-hand end.

FIG. 4 shows a cross section, on a greatly enlarged scale, through theshaft of an endoscope 40, and, for the sake of clarity of the drawing, aslightly shorter spacer 20′ is shown here separating the two rod lenses18 and 18′ from one another.

From the cross-sectional view in FIG. 4 it will be evident that the unit10′ is inserted after shrinkage into the tubular shaft 42 received inthe outer tube 44. The external diameter is chosen in such a way that asmall gap 52 is present between the outside face of the shrunk tube 12and the inside face 56 of the tubular shaft 42.

In FIG. 4, for the sake of clarity of the drawing, this gap 52 is shownmuch larger than it really is.

The width of the gap is chosen such that the shrunk unit 10′ can bepushed into the tubular shaft 42 easily, or at any rate with minimalresistance.

FIG. 4 shows, on the left-hand side, that the unit 10′ is fixed on theinside face 56 of the tubular shaft 42 via an adhesive 54. The adhesive54 can either be introduced through openings (not shown here) from theoutside or can be applied to the shrunk unit 10′ before the latter isinserted into the tubular shaft 42.

The right-hand end of FIG. 4 shows that the unit 10′ is fixed to theinside face 56 of the tubular shaft 52 by further shrinkage of the tubeand associated radial expansion, in which case, as has already beenmentioned, the shrinkable tube can be geometrically designed in such away that, for example by provision of beads, incisions or otherconfigurations which promote expansion at predetermined locations, thisexpansion takes place in a specific manner during the further shrinkingprocess.

This possibility is chosen when the material 14 of the tube 12 permitstwo shrinking processes, namely a first or preliminary shrinking processfor fixing the components to one another, for example in the retainingdevice 30 shown in FIG. 2, and then, after insertion into the tubularshaft 42 as shown in FIG. 4, a further shrinking and radial expansionfor filling the gap 52.

1. An endoscope, comprising: a tubular shaft, an optical system havingseveral components, said components of said optical system are containedin an interior of said tubular shaft, said components of said opticalsystem are surrounded by a support piece made of a shrunk material,wherein said shrunk material is a transparent material, said supportpiece made of said transparent material has a shape of a tube, and saidtube containing said components of said optical system has been shrunkprior to inserting said tube into said interior of said tubular shaft,for allowing a visual check of a position of said components relative toone another.
 2. The endoscope of claim 1, wherein said components aresurrounded by a single tube made of said transparent material.
 3. Theendoscope of claim 1, wherein said shrunk transparent tube containingsaid components is fixed to an inside face of said tubular shaft.
 4. Theendoscope of claim 3, wherein said tube being fixed to said inside faceof said tubular shaft by a radial expansion of said shrunk material. 5.The endoscope of claim 4, wherein said shrunk tube containing saidseveral components has in at least one area a configuration effecting aradial expansion during an axial shrinkage of said tube already insertedinto said hollow shaft.
 6. The endoscope of claim 5, wherein saidconfiguration being at least one of thickened parts, beads and incisionsof said transparent material.
 7. An endoscope, comprising: a tubularshaft having an interior; an optical system including a plurality ofcomponents positioned in the interior of said shaft; a support piececomprising a shrunk material enclosing said optical system to fit intothe interior of said tubular shaft and providing support for saidoptical system; wherein said optical system is enclosed and supported bysaid shrunk material prior to insertion into said interior of saidtubular shaft; and wherein said shrunk material is either transparent ortranslucent such that visual inspection of said plurality of componentsrelative to each other may be conducted prior to insertion into saidinterior of said tubular shaft.
 8. The endoscope of claim 7, whereinsaid plurality of components is surrounded by a single tube made of saidtransparent or translucent material.
 9. The endoscope of claim 7,wherein said shrunk transparent or translucent material containing saidplurality of components is affixed to an inside face of said tubularshaft.
 10. The endoscope of claim 9, wherein said shrunk transparent ortranslucent material is affixed to said inside face of said tubularshaft by a radial expansion of said shrunk transparent or translucentmaterial.
 11. The endoscope of claim 10, wherein said shrunk transparentor translucent material containing said plurality of components has inat least one area a configuration effecting a radial expansion during anaxial shrinkage of said transparent or translucent material alreadyinserted into the interior of said tubular shaft.
 12. The endoscope ofclaim 11, wherein said configuration being at least one of thickenedparts, beads and incisions of said transparent or translucent material.